Installation of gate valves, globe valves and check valves

Gate valve, also known as gate valve, is a valve that uses a gate to control opening and closing. It adjusts pipeline flow and opens and closes pipelines by changing the pipeline cross-section. Gate valves are mostly used in pipelines with fully open or fully closed fluid media. There is generally no direction requirement for gate valve installation, but it cannot be installed upside down.

A globe valve is a valve that uses a valve disc to control opening and closing. By changing the gap between the valve disc and the valve seat, that is, changing the size of the channel cross-section, the medium flow or medium channel is cut off. When installing a stop valve, attention must be paid to the flow direction of the fluid.
The principle that must be followed when installing a stop valve is that the fluid in the pipeline passes through the valve hole from bottom to top, commonly known as “low in and high out”, and reverse installation is not allowed.

Check valve, also known as check valve and one-way valve, is a valve that automatically opens and closes under the pressure difference between the front and rear of the valve. Its function is to allow the medium to flow in only one direction and prevent the medium from flowing back in the opposite direction. According to different structures, check valves include lift, swing and butterfly clamp check valves. Lift check valves are divided into horizontal and vertical types. When installing the check valve, you should also pay attention to the flow direction of the medium and do not install it backwards.

Installation of pressure reducing valve

The pressure reducing valve is a valve that reduces the inlet pressure to the required outlet pressure through adjustment and automatically maintains a stable outlet pressure by relying on the energy of the medium itself.

From a fluid mechanics perspective, a pressure reducing valve is a throttling element that can change local resistance. That is, by changing the throttling area, the flow rate and kinetic energy of the fluid are changed, thereby producing different pressure losses, thereby achieving the purpose of pressure reduction. Then, relying on the adjustment of the control and regulation system, the spring force is used to balance the fluctuation of the pressure behind the valve, so that the pressure behind the valve remains constant within a certain error range.

Installation of pressure reducing valve

1. The vertically installed pressure reducing valve group is generally installed along the wall at an appropriate height from the ground; the horizontally installed pressure reducing valve group is generally installed on a permanent operating platform.

2. Use shaped steel to install on the wall outside the two control valves (commonly used for stop valves) to form a bracket. The bypass pipe is also stuck on the bracket and leveled.

3. The pressure reducing valve should be installed upright on the horizontal pipeline and must not be tilted. The arrow on the valve body should point to the direction of medium flow and cannot be installed backwards.

4. Stop valves and high and low pressure pressure gauges should be installed on both sides to observe the pressure changes before and after the valve. The diameter of the pipe after the pressure reducing valve should be 2#-3# larger than the diameter of the inlet pipe in front of the valve, and a bypass pipe should be installed to facilitate maintenance.

5. The pressure equalizing pipe of the diaphragm pressure reducing valve should be connected to the low pressure pipeline. Low-pressure pipelines should be equipped with safety valves to ensure safe operation of the system.

6. When used for steam decompression, a drainage pipe must be installed. For pipeline systems with higher purification requirements, a filter should be installed in front of the pressure reducing valve.

7. After the pressure reducing valve group is installed, the pressure reducing valve and safety valve should be pressure tested, flushed and adjusted according to the design requirements, and the adjustments should be marked.

8. When flushing the pressure reducing valve, close the pressure reducer inlet valve and open the flushing valve for flushing.

Trap installation

The basic function of the steam trap is to discharge condensed water, air and carbon dioxide gas in the steam system as quickly as possible; at the same time, it can automatically prevent steam leakage to the greatest extent. There are many types of traps, each with different capabilities.

According to the different working principles of steam traps, they can be divided into the following three types:

Mechanical: Acts according to changes in the condensate level in the trap, including:

Float type: The float is a closed hollow sphere.

Upward-opening float type: The float is barrel-shaped and opens upward.

Opening downward float type: The float is barrel-shaped with the opening downward.

Thermostatic type: works according to changes in liquid temperature, including:

Bimetallic sheet: The sensitive element is a bimetallic sheet.

Vapor pressure type: The sensitive element is a bellows or cartridge, which is filled with volatile liquid.

Thermodynamic type: Acts based on changes in the thermodynamic properties of the liquid.

Disc type: Due to the different flow rates of liquid and gas under the same pressure, different dynamic and static pressures are generated to drive the disc valve to move.

Pulse type: When condensate of different temperatures passes through the two-pole series throttle orifice plates, different pressures are formed between the two poles of the throttle orifice plates, driving the valve disc to move.

Trap installation

1. Stop valves (stop valves) should be installed at the front and rear, and a filter should be installed between the trap and the front stop valve to prevent dirt in the condensate water from clogging the trap.

2. An inspection pipe should be installed between the trap and the rear stop valve to check whether the trap is working properly. If a large amount of steam comes out when you open the inspection tube, the trap is damaged and needs repair.

3. The purpose of setting up a bypass pipe is to discharge a large amount of condensed water during startup and reduce the drainage load of the trap.

4. When the drain valve is used to remove condensate from heating equipment, it should be installed at the lower part of the heating equipment so that the condensate water pipe returns vertically to the drain valve to prevent water accumulation in the heating equipment.

5. The installation location should be as close to the drainage point as possible. If the distance is too far, air or steam can accumulate in the long, thin pipe in front of the trap.

6. When the steam main horizontal pipe is too long, drainage issues should be considered.